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UPSTREAM: arm64: erratum: Work around Falkor erratum #E1003 in trampoline code

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We rely on an atomic swizzling of TTBR1 when transitioning from the entry
trampoline to the kernel proper on an exception. We can't rely on this
atomicity in the face of Falkor erratum #E1003, so on affected cores we
can issue a TLB invalidation to invalidate the walk cache prior to
jumping into the kernel. There is still the possibility of a TLB conflict
here due to conflicting walk cache entries prior to the invalidation, but
this doesn't appear to be the case on these CPUs in practice.

Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Tested-by: Laura Abbott <labbott@redhat.com>
Tested-by: Shanker Donthineni <shankerd@codeaurora.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>
(cherry picked from git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git
 commit d1777e686a)

[ghackmann@google.com: replace runtime alternative_if with a
 compile-time check for Code Aurora's out-of-tree CONFIG_ARCH_MSM8996.
 Kryo needs this workaround too, and 4.4 doesn't have any of the
 upstream Falkor errata infrastructure needed to detect this at boot time.]
Signed-off-by: Greg Hackmann <ghackmann@google.com>
Signed-off-by: Todd Poynor <toddpoynor@google.com>

Change-Id: Iaf244a364b22d386b54368f88b73e39d295de49f
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
This commit is contained in:
Will Deacon
2017-11-14 14:29:19 +00:00
committed by Greg Kroah-Hartman
parent c27a225834
commit 04b77fe9ae
1 changed files with 10 additions and 0 deletions
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10
arch/arm64/kernel/entry.S
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@@ -910,6 +910,16 @@ __ni_sys_trace:
sub \tmp, \tmp, #(SWAPPER_DIR_SIZE + RESERVED_TTBR0_SIZE)
bic \tmp, \tmp, #USER_ASID_FLAG
msr ttbr1_el1, \tmp
#ifdef CONFIG_ARCH_MSM8996
/* ASID already in \tmp[63:48] */
movk \tmp, #:abs_g2_nc:(TRAMP_VALIAS >> 12)
movk \tmp, #:abs_g1_nc:(TRAMP_VALIAS >> 12)
/* 2MB boundary containing the vectors, so we nobble the walk cache */
movk \tmp, #:abs_g0_nc:((TRAMP_VALIAS & ~(SZ_2M - 1)) >> 12)
isb
tlbi vae1, \tmp
dsb nsh
#endif /* CONFIG_ARCH_MSM8996 */
.endm
.macro tramp_unmap_kernel, tmp